Fiber materials are used for many different applications in a wide variety of industries, such as the commercial aviation, recreation, industrial and transportation industries. Commonly-used fiber materials for these and other applications include carbon fiber, cellulosic fiber, glass fiber, metal fiber, ceramic fiber and aramid fiber, for example.
Carbon fiber is routinely manufactured with sizing agents to protect the material from environmental degradation. Additionally, other physical stresses can compromise carbon fiber integrity such as compressive forces and self abrasion. Many sizing formulations used to protect carbon fibers against these vulnerabilities are proprietary in nature and are designed to interface with specific resin types. To realize the benefit of carbon fiber material properties in a composite, there must be a good interface between the carbon fibers and the matrix. The sizing employed on a carbon fiber can provide a physico-chemical link between fiber and the resin matrix and thus affects the mechanical and chemical properties of the composite.
However, most conventional sizing agents have a lower interfacial strength than the carbon fiber material to which they are applied. As a consequence, the strength of the sizing and its ability to withstand interfacial stress ultimately determines the strength of the overall composite. Thus, using conventional sizing, the resulting composite will generally have a strength less than that of the carbon fiber material.
It would be useful to develop sizing agents and processes of coating the same on carbon fiber materials to address some of the issues described above as well as to impart desirable characteristics to the carbon fiber materials. The present invention satisfies this need and provides related advantages as well.